【正文】 它的特點在于在一個汽缸中有兩個燃燒室，當沖入的混合氣體過多是，備用燃燒室就會將多余的混合氣體儲存起來。循環(huán)過程中，轉子的旋轉一周，會出有三個沖程，而且在轉子的正反兩面產生壓力。在二沖程循環(huán)中，燃料和空氣的混合氣體在活塞在汽缸中下行時進入曲軸箱。事實上，現(xiàn)在發(fā)動機中，基本的效率都不會超過 40％。大多數(shù)柴油機都是采用四沖程，但卻與奧托式四沖程不 一樣。當活塞上行到最高點時，燃燒室的體積達到最小，火花塞就會點燃混合氣體，燃燒產生的膨脹壓力會作用在活塞上，使活塞遠離缸蓋，這就是第三個行程。小型的發(fā)動機有時需要手動的進行多次使離合器的松脫才能發(fā)動。由于燃燒室的溫度太高，所有的發(fā)動機都必須有相應的冷卻系統(tǒng)。在有直噴裝置的發(fā)動機上，燃料會通過噴射系統(tǒng)在正確的時刻噴入汽缸或者進氣管。不同的發(fā)動機會有一個到二十四個等的氣缸。壓縮燃燒室是由一個一段由缸蓋另一端由活塞之間的空間所形成。最常見的內燃機有四種：奧托循環(huán)式發(fā)動機，柴油機，轉子發(fā)動機和煤氣機?，F(xiàn)將設計中所做的工作簡要介紹如下：柴油機活塞加工工藝合理性是很重要的，通過對零件的作用及工藝方案分析，擬定毛坯的制造形式及工藝路線，通過分 析、比較，采用了相對集中加工工藝方案，最終確定比較合理的機械加工工藝路線。 the diesel engine, named after the Frenchborn German engineer Rudolf Christian Karl Diesel, operates on a different principle and usually uses oil as a fuel. It is employed in electricgenerating and marinepower plants, in trucks and buses, and in some automobiles. Both Ottocycle and diesel engines are manufactured in 本科 生畢業(yè) 設計（論文）外文翻譯 2 twostroke and fourstroke cycle essential parts of Ottocycle and diesel engines are the same. The bustion chamber consists of a cylinder, usually fixed, that is closed at one end and in which a closefitting piston slides. The inandout motion of the piston varies the volume of the chamber between the inner face of the piston and the closed end of the cylinder. The outer face of the piston is attached to a crankshaft by a connecting rod. The crankshaft transforms the reciprocating motion of the piston into rotary motion. In multicylindered engines the crankshaft has one offset portion, called a crankpin, for each connecting rod, so that the power from each cylinder is applied to the crankshaft at the appropriate point in its rotation. Crankshafts have heavy flywheels and counterweights, which by their inertia minimize irregularity in the motion of the shaft. An engine may have from 1 to as many as 28 cylinders. The fuel supply system of an internalbustion engine consists of a tank, a fuel pump, and a device for vaporizing or atomizing the liquid fuel. In Ottocycle engines this device is either a carburetor or, more recently, a fuelinjection system. In most engines with a carburetor, vaporized fuel is conveyed to the cylinders through a branched pipe called the intake manifold and, in many engines, a similar exhaust manifold is provided to carry off the gases produced by bustion. The fuel is admitted to each cylinder and the waste gases exhausted through mechanically operated poppet valves or sleeve valves. The valves are normally held closed by the pressure of springs and are opened at the proper time during the operating cycle by cams on a rotating camshaft that is geared to the crankshaft. By the 1980s more sophisticated fuelinjection systems, also used in diesel engines, had largely replaced this traditional method of supplying the proper mix of air and fuel. In engines with fuel injection, a mechanically or electronically controlled monitoring system injects the appropriate amount of gas directly into the cylinder or inlet valve at the appropriate time. The gas vaporizes as it enters the cylinder. This system is more fuel efficient than the carburetor and produces less pollution. In all engines some means of igniting the fuel in the cylinder must be provided. For example, the ignition system of Ottocycle engines described below consists of a source of lowvoltage, directcurrent electricity that is connected to the primary of a transformer called an ignition coil. The current is interrupted many times a second by an automatic switch called the timer. The pulsations of the current in the primary induce a pulsating, highvoltage current in the secondary. The highvoltage current is led to each cylinder in turn by a rotary switch called the distributor. The actual ignitio